Methods of generating a gas in a plugging composition to improve its sealing ability in a downhole permeable zone

Abstract

Methods of servicing a wellbore include generating gas in a plugging composition in situ within a permeable zone in the wellbore, thereby improving the ability of the plugging composition to seal the permeable zone. The gas may be generated via a chemical reaction by, for example, introducing first and second reactants to the plugging composition that can react at ambient temperatures in the wellbore. In an embodiment, the first and second reactants are concurrently pumped into the wellbore via separate flow paths within two concentric conduits to the permeable zone where they are allowed to contact each other in the presence of the plugging composition. In another embodiment, the first reactant, the second reactant, and a retarder for slowing the reaction between the two reactants are concurrently pumped to the permeable zone. In yet another embodiment, one of the reactants is encapsulated to delay a reaction between the two reactants.

What is claimed is: 
     
       1. A method of servicing a wellbore, comprising:
 circulating a drilling fluid in the wellbore; 
 upon loss of circulation of the drilling fluid, introducing a plugging composition into the wellbore; 
 allowing the plugging composition to flow into a permeable zone in the wellbore; and 
 generating a gas in the plugging composition in situ within the permeable zone; wherein said generating the gas comprises introducing a first reactant and a second reactant to the plugging composition, and wherein the volume of the plugging composition increases by from about 0.1% to about 50% by total volume of the composition at a pressure of from about 3,000 psi to about 5,000 psi. 
 
     
     
       2. The method of  claim 1 , wherein the gas is generated via a chemical reaction. 
     
     
       3. The method of  claim 1 , wherein the first reactant comprises a nitrogen generating material comprising hydrazine, a hydrazine salt of an acid, azodicarbonamide, azobis(isobutyronitrile), p-toluene sulfonyl hydrazide, p-toluene sulfonyl semicarbazide, carbohydrazide, p-p′-oxybis(benzenesulfonylhydrazide), an ammonium salt of an organic or inorganic acid, hydroxylamine sulfate, carbamide, or combinations thereof. 
     
     
       4. The method of  claim 1 , wherein the second reactant comprises an alkaline aqueous solution. 
     
     
       5. The method of  claim 1 , wherein the second reactant comprises an oxidizing agent. 
     
     
       6. The method of  claim 1 , wherein the first reactant comprises a hydrogen generating material comprising aluminum, calcium, zinc, magnesium, lithium, sodium, potassium, or combinations thereof. 
     
     
       7. The method of  claim 6 , wherein the second reactant comprises an alkaline aqueous solution. 
     
     
       8. The method of  claim 1 , wherein the first reactant comprises a carbon dioxide generating material comprising ammonium, alkali metal, alkaline earth metal and transition metal salts of carbonate and bicarbonate, or combinations thereof. 
     
     
       9. The method of  claim 8 , wherein the second reactant comprises an acid or acid generating material. 
     
     
       10. The method of  claim 8 , wherein the second reactant comprises acetic acid; citric acid; tartaric acid; alkali, alkaline earth and transition metal salts of dihydrogen phosphate, acid pyrophosphate; or combinations thereof. 
     
     
       11. The method of  claim 1 , wherein the first and second reactants are concurrently pumped into the wellbore via separate flow paths within two concentric conduits to the permeable zone where they are allowed to contact each other in the presence of the plugging composition. 
     
     
       12. The method of  claim 11 , wherein the plugging composition is pumped to the permeable zone ahead of the first and second reactants. 
     
     
       13. The method of  claim 11 , wherein the plugging composition is pumped to the permeable zone concurrent with pumping the first and second reactants. 
     
     
       14. The method of  claim 1 , wherein the plugging composition comprises a cement composition that also serves as the second reactant. 
     
     
       15. The method of  claim 1 , wherein the first reactant comprises an aluminum powder. 
     
     
       16. The method of  claim 1 , wherein the first reactant and the second reactant are concurrently pumped to the permeable zone, and wherein the first reactant, the second reactant, or both are encapsulated to delay a reaction between the first reactant and the second reactant. 
     
     
       17. The method of  claim 16 , wherein the first reactant comprises a nitrogen generating compound. 
     
     
       18. The method of  claim 16 , wherein the second reactant comprises an alkali or alkaline earth metal salt of a peroxide, persulfate, perborate, hypochlorite, hypobromite, chlorite, chlorate, iodate, bromate, chloroaurate, arsenate, antimonite, or molybate anion, or combinations thereof. 
     
     
       19. The method of  claim 16 , wherein the second reactant comprises a solid encapsulated in a coating material comprising a wax, a drying oil, a polyurethane, a crosslinked partially hydrolyzed polyacrylic, or combinations thereof. 
     
     
       20. The method of  claim 16 , wherein the second reactant comprises an aqueous solution encapsulated in a porous solid material through which the aqueous solution is capable of diffusing. 
     
     
       21. The method of  claim 1 , wherein the plugging composition comprises a cement composition. 
     
     
       22. The method of  claim 1 , wherein the plugging composition comprises an oil, a hydratable polymer, an organophilic clay, and a water-swellable clay. 
     
     
       23. The method of  claim 1 , wherein the plugging composition comprises an activator and a drilling fluid comprises a gas-generating material. 
     
     
       24. The method of  claim 23 , wherein the plugging composition comprises latex, organophilic bentonite, hydroxylethyl cellulose, soda ash, a dispersant, and the activator. 
     
     
       25. The method of  claim 1 , wherein the plugging composition comprises a crosslinked polymer having a diameter greater than or equal to about 1 mm in size. 
     
     
       26. The method of  claim 25 , wherein the crosslinked polymer comprises crosslinked polyacrylamide. 
     
     
       27. The method of  claim 1 , wherein the plugging composition comprises a crosslinked polyacrylamide; crosslinked polyacrylate; crosslinked hydrolyzed polyacrylonitrile; salts of carboxyalkyl starch, for example, salts of carboxymethyl starch; salts of carboxyalkyl cellulose, for example, salts of carboxymethyl cellulose; salts of any crosslinked carboxyalkyl polysaccharide; crosslinked copolymers of acrylamide and acrylate monomers; starch grafted with acrylonitrile and acrylate monomers; crosslinked polymers of two or more of allylsulfonate, 2-acrylamido-2-methyl-1-propanesulfonic acid, 3-allyloxy-2-hydroxy-1-propane-sulfonic acid, acrylamide, and acrylic acid monomers; or combinations thereof. 
     
     
       28. The method of  claim 27 , wherein the plugging composition comprises an alkali metal metasilicate compound, an alkali metal silicate compound, an alkali metal aluminate, or combinations thereof. 
     
     
       29. The method of  claim 27 , wherein the plugging composition comprises sodium silicate. 
     
     
       30. The method of  claim 1 , wherein the permeable zone is in a subterranean formation penetrated by the wellbore, a wall of a conduit disposed in the wellbore, a column disposed in the wellbore, a microannulus in the wellbore, or combinations thereof. 
     
     
       31. The method of  claim 1 , wherein the permeable zone comprises a fissure, a crack, a fracture, a vug, a streak, a flow channel, a void, a perforation, or combinations thereof. 
     
     
       32. The method of  claim 1 , wherein the gas is generated by gasifying a liquefied gas included in the plugging composition. 
     
     
       33. The method of  claim 1 , wherein the first reactant and the second reactant are capable of reacting at ambient temperatures in the wellbore to produce the gas. 
     
     
       34. The method of  claim 1 , wherein the first reactant, the second reactant, and a retarder for delaying a reaction between the first reactant and the second reactant are concurrently pumped to the permeable zone. 
     
     
       35. The method of  claim 34 , wherein the retarder comprises sorbitan monooleate, glycerol monoricinoleate, sorbitan monoricinoleate, sorbitan monotallate, pentaerythritol monoricinoleate, sorbitan monoisostearate, glycerol monostearate, sorbitan monostearate, or combinations thereof. 
     
     
       36. A method of servicing a wellbore, comprising:
 circulating a drilling fluid within the wellbore; 
 upon loss of circulation of the drilling fluid introducing a plugging composition to the wellbore; 
 allowing the plugging composition to flow into a permeable zone in the wellbore; and 
 generating a gas in a plugging composition in situ within the permeable zone; wherein said generating the gas comprises introducing a first reactant and a second reactant to the plugging composition; wherein the first reactant, the second reactant, or both are encapsulated with at least one material for delaying the gas generating reaction and wherein the material is selected from the group consisting of a drying oil, a polyurethane, a crosslinked partially hydrolyzed polyacrylic, a water degradable compound or polymer, diatomaceous earth, zeolites, silica, alumina, metal salts of alumino-silicates, clays, hydrotalcite, styrenedivinylbenzene based materials, cross-linked polyalkylacrylate esters, cross-linked modified starches, EDPM rubber, polyvinyldichloride, nylon, polyurethanes, and combinations thereof, and wherein the volume of the plugging composition increases by from about 0.1% to about 50% by total volume of the composition at a pressure of from about 3,000 psi to about 5,000 psi. 
 
     
     
       37. A method of improving a plugging composition, comprising:
 circulating a drilling fluid within the wellbore; 
 upon loss of circulation of the drilling fluid introducing a plugging composition to the wellbore; 
 allowing the plugging composition to flow into a permeable zone in the wellbore and generating gas in the plugging composition in situ within the permeable zone to increase friction between the plugging composition and an adjacent surface in a wellbore upon a loss of circulation in the wellbore; and wherein said generating the gas comprises introducing a first reactant and a second reactant to the plugging composition; and wherein the volume of the plugging composition increases by from about 0.1% to about 50% by total volume of the composition at a pressure of from about 3,000 psi to about 5,000 psi. 
 
     
     
       38. The method of  claim 37 , wherein the generation of the gas increases a resiliency of the plugging composition. 
     
     
       39. The method of  claim 37 , wherein the permeable zone is in a subterranean formation penetrated by the wellbore, a wall of a conduit disposed in the wellbore, a column disposed in the wellbore, a microannulus in the wellbore, or combinations thereof. 
     
     
       40. The method of  claim 37 , wherein the permeable zone comprises a fracture, a fissure, a crack, a vug, a streak, a flow channel, a void, or combinations thereof. 
     
     
       41. The method of  claim 37 , wherein an amount of force required to dislodge the plugging composition from the permeable zone after the gas is generated is greater than an amount of force required to dislodge the same plugging composition before the gas is generated. 
     
     
       42. The method of  claim 37 , wherein the plugging composition remains in the permeable zone for a longer duration of time when a force is applied to it after the gas is generated than before the gas is generated. 
     
     
       43. A method of servicing a wellbore, comprising:
 circulating a drilling fluid within the wellbore; 
 upon loss of circulation of the drilling fluid introducing a plugging composition to the wellbore; 
 allowing the plugging composition to flow into a permeable zone in the wellbore and generating a gas in a plugging composition in situ within the permeable zone, wherein the plugging composition expands to fill a cross-section of the permeable zone, thus blocking the flow of fluid through the zone and wherein the permeable zone is a loss circulation zone, wherein the volume of the plugging composition increases by from about 0.1% to about 50% by total volume of the composition at a pressure of from about 3,000 psi to about 5,000 psi. 
 
     
     
       44. The method of  claim 36 , wherein the plugging composition comprises a crosslinked polyacrylamide; crosslinked polyacrylate; crosslinked hydrolyzed polyacrylonitrile; salts of carboxyalkyl starch, for example, salts of carboxymethyl starch; salts of carboxyalkyl cellulose, for example, salts of carboxymethyl cellulose; salts of any crosslinked carboxyalkyl polysaccharide; crosslinked copolymers of acrylamide and acrylate monomers; starch grafted with acrylonitrile and acrylate monomers; crosslinked polymers of two or more of allylsulfonate, 2-acrylamido-2-methyl-1-propanesulfonic acid, 3-allyloxy-2-hydroxy-1-propane-sulfonic acid, acrylamide, and acrylic acid monomers; or combinations thereof.